Definition of "pseudoprime"

(mathematics) An integer that possesses at least one characteristic of a prime number without actually being prime. The characteristic is typically chosen to make such "false primes" very rare.  examples

(mathematics, specifically) A Fermat pseudoprime; a composite integer n satisfying b n − 1 ≡ 1 ( mod n ) for some integer b such that b > 1.  examples

Being such an integer.  examples